As is well known, the knee joint, although frequently considered a hinge joint, actually comprises two joints, lateral and medial, between the femur and tibia, and one arthrodial joint between the patella and femur. The primary movements of the knee comprise flexion, i.e. rearward rotational movement of the tibia relative the femur, and extension, i.e. forward rotational movement of the tibia relative the femur.
The flexion and extension movements of the knee joint are not simply pivotal movements about a fixed axis. During flexion, the axis around which movement takes place shifts backward, and during extension it shifts forward. This is different from a more typical hinge joint, such as an elbow, where the axis of rotation does not shift. As full extension is reached, the tibia is rotated inward or rearward and the joint in effect is disposed in a "locked" position with the ligaments taut. This gives the joints greater stability in the extended position. As flexion is initiated, the tibia initially lowers or moves downwardly with the small external rotation of the tibia which "unlocks" the joint and subsequently the tibia rotates or rolls about the joint to full flexion. Accordingly, the initial unlocking of the knee joint during flexion proceeds actual full rotation of the knee.
Due to the above complexity of knee movement, for a knee brace to more fully support the knee joint of the user and facilitate rehabilitation and/or prevent re-injury of an injured knee joint, the brace must more closely analogize the movement of the knee than a simple hinge mechanism. With specific relation to post-surgical applications, the requirement for such analogized movement becomes acute for the proper rehabilitation of the knee joint. Additionally, for such post-surgical applications, the knee brace should be relatively lightweight to avoid overly hindering the user's mobility yet possess sufficient structural strength to adequately support the knee joint during rehabilitation. Further, knee braces used in conjunction with such surgical applications should be easily and quickly adjustable to conform to the particular size of the user's leg and to maintain such adjusted size so that the knee brace may be removed from the leg during bathing and showering and subsequently reattached to the leg with a minimum amount of difficulty.
In recognizing the need for an effective post-surgical knee brace, various knee braces have been introduced into the marketplace. Such contemporary knee braces, however, have generally failed to provide the precise simulation of knee joint movement as described above or have comprised relatively heavy, bulky apparatus, thereby detracting from the user's mobility while wearing the brace. Further, such contemporary designs have typically failed to possess sufficient adjustability so as to be quickly and easily interfaceable to the leg of the user or to maintain an adjusted configuration so as to permit periodic removal and reattachment of the knee brace to the user's leg.